Biomedical subjects

N Schüler

Publications and source records attributed to N Schüler.

6 recordsLinked to original sources

PubMed1998

Attachment formation following replantation of cultured cells into periodontal defects--a study in minipigs.

Regeneration processes in the periodontium occur by the interaction of different cell populations. It is known that these cells are also capable of forming new periodontal tissue after culture in vitro. The present study investigated whether replanted cultured cells from the periodontium could contribute to attachment formation. Primary cell cultures from alveolar bone and periodontal ligament were obtained from 11 minipigs. Experimentally induced furaction and interdental defects (n = 168) were treated in groups: (a) flap surgery, replantation of alveolar bone cells, and covering of the defects with Teflon membranes (ABC group); (b) flap surgery, replantation of periodontal ligament cells and membranes (PLC group); (c) flap surgery, bone gelatin (carrier material) and membranes (BG group); (d) flap surgery and membranes (NBG group); (e) flap surgery (FS group); and (f) no treatment (NT group). The defects were clinically and histologically (polyfluorochrome labeling) assessed after 10, 30, and 90 days. In the ABC group, initial calcified tissue formation at the roots was apparent after only 8 days. Marked new formation of cementum and alveolar bone and the development of a new attachment were observed after 90 days. In the BG and the NBG groups, wound healing varied depending on membrane healing and the morphology of the defects, which led to significantly poorer and variable results. Similar results were found in the PLC group, although some defects showed extensive cementum and bone formation. Defects in the FS and the NT groups healed largely by epithelialization. The study shows that replantation of cultured alveolar bone cells leads to formation of new cementum and bone, which, in turn, leads to formation of a new attachment. It is likely that the cells stabilize the tissue formation in the defect or on the root surface in the early phase of wound healing and prevent epithelial downgrowth. Results also show that regeneration in the periodontium is determined by the availability of (precursor) cells capable of forming calcified tissues.

Alveolar Process↗

PubMed1995

Formation of differentiated tissues in vivo by periodontal cell populations cultured in vitro.

The periodontium contains heterogeneous mesenchymal cell populations with various differentiation potentials. The capacity of these cells for tissue formation as well as the origin of their precursors are still not entirely defined. In this study, cells originating from different periodontal tissues were cultured in vitro, and tissue formation in vivo following orthotopic re-implantation was investigated. Cells were recovered from the alveolar bone and periodontal ligament tissue of six minipigs, and cultured cells were then grown on extracted dental roots from the homologous animals by means of co-culture in vitro. Each minipig received 2 roots covered with alveolar bone cells, 2 roots covered with periodontal ligament cells, and 2 control roots (without cells) implanted into palatal bone defects. Intravital fluorochrome labeling was performed, and two minipigs were histologically examined after 2, 4, and 12 weeks in each case. Controls showed widespread resorption and ankylosis, whereas roots covered with cultured periodontal cells exhibited tissue formation in vivo. Alveolar bone cells synthesized a calcified cellular tissue resembling cellular cementum, suggesting that cells within this population might differentiate into cementoblasts when reimplanted with a dental substrate in vivo. Periodontal ligament cells exhibited no calcified tissue formation in vivo, but cells synthesized a connective tissue with orientated fiber bundles attached to both host bone and root, resembling periodontal ligament.

Alveolar Process↗

PubMed1992

[The synthesis of collagenous and noncollagenous proteins by cells from the periodontium].

Synthesis of collagenous and noncollagenous proteins by cells originating from the alveolar bone (AB-cells) and from the periodontal ligament (PDL-cells) of 8 minipigs was analyzed in primary cell cultures. Incorporation of 3H-proline into proteins recovered from cell extracts showed, that 13.7% of protein synthesized by AB-cells and 8.0% of protein synthesized by PDL-cells were collagens. In both cell lines relative amounts of collagens synthesized decreased significantly on subculturing (AB-cells: 9.3%, PDL-cells: 6.0%). Preincubation of 2nd subculture AB-cells with beta-glycerophosphate had no significant effect on collagen synthesis. Considering the fact that relative amounts of collagen recovered from cell extracts represent only 10-20% of collagen recovered from whole culture (i.e. cells and culture medium), we suggest that collagen synthesis is an important component of in vitro-protein synthesis of cells originating from the alveolar bone and the periodontal ligament.

Alveolar Process↗

PubMed1990

Correlation between caries prevalence (DMFS) and periodontal condition (CPITN) in more than 2000 patients.

The CPITN (Community Periodontal Index of Treatment Needs) and DMFS (Decayed-Missing-Filled Surfaces) index were evaluated simultaneously to provide information on the mutual influences of periodontal disease and caries. With the aid of an electronic database system the data of the caries index and periodontal index of more than 2000 patients aged between 18 and 80 years were stored and calculated. As expected, the CPITN and DMFS values increased with age. When the CPITN was selected as a reference the DMFS was found to change with increasing CPITN. With the examination method used in this study no correlation could be established between the prevalence of caries and periodontal condition, although both conditions have a common aetiological factor: microbial plaque.

Adolescent↗

PubMed1985

[Computed tomography of the heart. Technic for quantitative evaluation of the perfusion of the ischemic myocardial region. Experimental basis].

A CT standard procedure has been developed in six series of experiments, using 62 anaesthetised dogs in order to quantitative relative blood flow through ischaemic heart muscle. Measurements of cardiac dynamics by means of contrast media were less strictly controlled. The use of the standardised procedures with contrast injections is necessary because of the variable perfusion and washout intervals of the contrast in normal and ischaemic myocardium.

Animals↗

PubMedDate not supplied

Increment technique for extended Class V restorations: an experimental study.

The application and polymerization of composite or polyacid-modified resin composites in thin layers (increment technique) for filling cavities might partially compensate for the stress associated with polymerization shrinkage. In this study, the effect of this technique on the marginal integrity of Class V polyacid-modified composite restorations was investigated. In 30 extracted premolars, extended Class V cavities were prepared with the apical margin in root dentin and the coronal margin in enamel. They were then subjected to different treatments (10 teeth in each case): a) placement and polymerization of a thin resin composite layer (Dyract-Dyract PSA) in the coronal part of the cavity (plus one increment for the residual part) (Group 1), b) a thin layer at the apical part of the cavity (plus one increment for the residual part) (Group 2) and c) restoration of the entire cavity with one increment (bulk technique) (Group 3). Following three days' storage in water, the teeth were subjected to cyclic thermal loading (4 degrees C <-> 55 degrees C, 2,000 cycles). The percentages of defective bonding detected along the total length of the restoration margin were assessed before and after thermocycling by scanning electron microscopy. Following loading and thermocycling, no significant differences were found at the restoration-enamel interface. Fewer gaps were found at the restoration-dentin interface in Group 1 (18.7 +/- 25.7%) and Group 2 (20.5 +/- 22.8%) compared to the reference Group 3 (42.2 +/- 30.6%) (Mann-Whitney U test: p<0.05). Moreover, there were no significant differences between the two increment groups (1 and 2). In a significantly larger number of cases, a completely intact dentin restoration margin was detected when a coronal increment (Group 1) (44.4%) was used instead of the bulk technique (Group 3) (13.6%) (Chi square test: p<0.05). These results indicate that gap formation can be significantly minimized by using an increment technique to restore extended Class V cavities with polyacid-modified composite materials.

Chi-Square Distribution↗